A vest is best year around as the water is the same temperature year around. The problem in the winter isn't the water it's the air temperature. If it's 60 degrees out, and the water is 76, that means you're going to be COLD when you get out of the water. A wetsuit doesn't protect against wind or anything, so you ideally want to get out of it right away and dry off, but then once you're out of it you have to put it back on, which is no easy task. With a vest it's an easy slip on and off. You can get out of the water, take off the vest, dry off quickly and throw on a jacket. Then when you want to go back in the water take off the jacket and put on your vest and you're good to go.